Claim · model-written summary
Freezing during stem or petiolar cooling caused severe irreversible water stress above the cooled zone.
- Taxon
- sunflower
Helianthus annuuse1 - Treatment
- freezinge3
- Outcome
- severe irreversible water stresse3
- Qualifier
- above the cooled zonee3
Not reportedMaterialGeneCompoundOrgan / stageInteractorInteractor roleSecond interactorSecond interactor roleComparatorSettingDirectionValue
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“using hydroponic sunflower plants”
e3“Leaf water status was unaffected by cooling stem or petiolar segments unless freezing occurred, when severe irreversible water stress developed above the cooled zone”
Title
C. R. BLACK Journal of Experimental Botany 1979. doi:10.1093/jxb/30.2.245
Other claims from this paper (12)
- Intervention effect Cooling the root system to 10 °C or below decreased leaf water potential by up to 7 × 10^5 Pa in hydroponic sunflower.
- Intervention effect Leaf water potential completely recovered after root cooling to 10 °C or below once freezing was avoided.
- Intervention effect Cooling stem or petiolar segments did not affect leaf water status unless freezing occurred.
- Intervention effect Leaves below the cooled zone were unaffected by stem or petiolar cooling.
- Intervention effect A rapid reduction of relative humidity to 60% induced a transient decrease in water potential (Ψ) of approximately 4.5 × 10^5 Pa in sunflower.
- Intervention effect A rapid reduction of relative humidity to 40% induced a transient decrease in water potential (Ψ) of 2.5 × 10^5 Pa in sunflower.
- Intervention effect The rapid humidity reduction was accompanied by large simultaneous increases in stomatal resistance in sunflower.
- Intervention effect No simultaneous transient effects were observed in the stem xylem during the rapid humidity reduction.
- Observation Petiolar resistance was low in sunflower petioles, about 0.04 Pa s cm−4.
- Observation Immature and senescent sunflower petioles had petiolar resistance up to 10 times larger than other petioles.
- Mechanism The petiolar resistance trend is attributed to the developmental stage and condition of the xylem.
- Mechanism The factor causing the transient foliar stress is located within the lamina, not in the stem xylem.